Blinky....I don't have muslin underneath, what you see is batting. I quilted the individual blocks prior to sewing them together. Lesley taught us how to do that...see page 214 of this thread.
Also..there may be some great information on the tris..they will be in each week's threads for the particular tri that you are working on. We did have conversation on several of them..if you look and have questions..just ask on that particular thread and it will pop back up for us and we'll give you any additional tips that we can think of.